... of the GPS track to High Falls. The extra little "peak" on the return trip (around mile point 3.9) was the side trip to Bill Branch Falls

The difference in elevation points going and coming is due to atmospheric changes. A GPS reads elevations based on barametric pressures, and the fact that the same points on the second half of the profile are about 200 feet "higher" than the same points on the first half show those weather changes (a storm was brewing to the north of us enroute home).